Electronic communication devices, such as cell phones are frequently used in public places. There is an increasing concern that the privacy of speech by using cell phone in such an open environment is not secured.
Masks equipped with a microphone are known. For example, U.S. Pat. No. 4,129,754 disclosed a hand-held reporting device for use in environments wherein a minimum of sound in connection with use of the device is a priority and in environments having a high level of noise intensity. The device includes a barrel with a bell-shaped top, the top is preferably set at an angle with respect to the barrel. A microphone is positioned at the end of the barrel remote from the bell-shaped top. The reporting device includes means for permitting pressurized air within the device to escape via an air communication channel from inside the device through a portion of the face piece of the device to the outside.
A more elaborated device has been disclosed in U.S. Pat. No. 3,796,842. It relates to a dictation mask adaptable for use by a court reporter, which is electrically connected to a recording apparatus for recording the voice of the dictator. The '842 patent teaches a generally spherically-shaped member providing an area for fitting on the face of the dictator and including a plurality of chambers serially in communication by means of apertures. Some of the chambers having muffling coils mounted therein for receiving the breath and voice of the dictator and muffling the sound there from. The muffling coil are provided with a plurality of spaced-apart breath exhaust passages, wherein, the spherically-shaped member is provided with a handle and the handle is provided with one of said plurality of chambers.
A problem in the prior art mask devices has been the signal distortion generated by the design of these devices. In particular, these devices have positioned the transducer or microphone in a way that is not optimized for sound fidelity. A further problem with prior art devices has been the air pressure build-up within the device when the user speaks with the device pressed against his or her mouth. The pressure tends to generate sound distortion and a low signal to noise ratio on the transducer. A second problem with existing designs is that noise created outside the device can be conducted in and create unwanted background noise during a conversation. Finally, existing designs allow significant leakage of sound to the environment outside the device.
There is therefore a need for a privacy mask having good sound fidelity, less pressure buildup, which also blocks outside sound from coming in and blocks inside voice from leaking out.